I860.] WBIGIIT LIAS AND BONE-BED. 375 



the Lias in any other land, both as regards the sequence of its different 

 zones of life, the richness of their faunas, and the fine preservation of 

 the animal remains contained therein, still the stratigraphical rela- 

 tions of these subdivisions, with the range and distribution of the 

 species in time and space, have not received from English pala3onto- 

 logists that measure of attention bestowed by the geologists of 

 the Continent on the Lias of their respective countries. In conse- 

 quence of this neglect, the correlation of many of our Liassic beds 

 with others of the same age on the Continent of Europe has not been 

 satisfactorily made out, and requires re -examination. 



Having dining the summer of 1859 made excursions to several of 

 the most typical localities in the counties of Warwick, Gloucester, 

 Glamorgan, Somerset, and Dorset, with the view to determine the 

 stratigraphical relations of certain beds of the Lower Lias containing 

 Echinodermata, I had the satisfaction of discovering, in this search, 

 the true position of the Saurian-bearing beds at Street and their 

 relation to the Ammonitiferous beds of the Lias, and finding the 

 Avicula contorta beds,- — the equivalent of the L T pper St. Cassian 

 beds and " Kossener Schichten," which have so long engaged the 

 attention of foreign geologists, thus establishing important palaconto- 

 logical correlations with a series of Continental deposits, — the Kosscn 

 strata, of great interest in both Triassic and Jurassic geology. 



Boundary of the Avicula contorta beds and the Lower Lias. — In 

 tho zone of Avicula contorta I include all the black shales with 

 their interstratified sandstones, limestones, and Bone-beds which lie 

 between the grey, green, and red marls of the Reaper, and the lowest 

 Ostrea beds in the zone of Ammonites pi 'anorhis ; and in the Lower 

 Lias I include all the marls, clays, and limestones lying between the 

 Ostrea beds at the base of the zone of Ammonites pJanorhis, and the 

 clays containing Ammonites raricostatus, and the upper beds of the 

 same zone, charged with Hippopodium ponderosum, Oryphxa ob- 

 liqua, and Cardiaia Listcri. 



In the Table at p. 876, 1 have arranged the zone of Avicida contorta 

 with the different zones of the Lower Lias, and, in parallel columns, 

 have added the designations by which some of these groups are 

 (listiu' r ui.slied by British geologists. 



[Tabu 



